Adjustable air gap in liquid quenching of melt-spun filaments

ABSTRACT

IN A SYSTEM FOR LIQUID QUENCHING MELT-SPUN FILAMENT IN A QUENCH TANK BELOW THE SPINNERET, A WEIR DEVICE IS ADJUSTABLY ATTACHED DIRECTLY TO THE SPIN BLOCK SO THAT THE VERTICAL DISTANCE BETWEEN THE SPINNING FACE AND THE UPPER SURFACE OF THE QUENCHING LIQUID IS DETERMINED BY THE ADJUSTMENT OF THE MOUNTING MEANS FOR THE WEIR DEVICE, REGARDLESS OF MINOR VARIATIONS IN THE VERTICAL SPACING BETWEEN THE SPINNERET AND THE QUENCH TANK.

J. B. NEVIN May 23, 1972 ADJUSTABLE AIR GAP IN LIQUID QUENCHING OF MELT-SPUN FILAMENTS Filed Dec. 16, 1969 KN m L [w 0 5 Q0 r O H E m W T N 1 w F. I A mm 1 m 2 n v? 9 Y I B EDEmE mDOmm 0 United States Patent 3,664,782 ADJUSTABLE AIR GAP IN LIQUID QUENCHING F MELT-SPUN FILAMENTS John B. Nevin, Guayama, Puerto Rico, assignor to Phillips Petroleum Company Filed Dec. 16, 1970, Ser. No. 98,626 Int. Cl. D01d 3/00 US. Cl. 425-71 Claims ABSTRACT OF THE DISCLOSURE In a system for liquid quenching melt-spun filaments in a quench tank below the spinneret, a weir device is adjustably attached directly to the spin block so that the vertical distance between the spinning face and the upper surface of the quenching liquid is determined by the adjustment of the mounting means for the weir device, regardless of minor variations in the vertical spacing between the spinneret and the quench tank.

This invention relates to apparatus for liquid quenching of melt-spun filaments.

In the liquid quenching of melt-spun synthetic thermoplastic filaments, it is frequently desirable that the air gap between the upper surface of the quenching liquid and the spinning face be less than one inch. Variations in the length of the air gap can result in undesired variations in the characteristics of the quenched filaments, and if the gap becomes too small the spinneret can become severely damaged by contact with the quenching liquid. It has been customary to utilize a Weir device on the quench tank to regulate the level of the quenching liquid. However, this has proven unsatisfactory in many installations where the configuration of the equipment makes it difiicult to accurately determine the height of the spinning face above the quenching liquid. This is particularly true of the spinning systems employing a gas shroud around the spinning face. Furthermore, it is frequently necessary to move the quench tank to permit cleaning of the spinning face, thus requiring a readjustment of the weir device upon replacing the quench tank. Where the quench tank is moved on wheels or on a track, the presence of any material on the wheels or the track will vary the air gap distance. The weight of the quench tank and the quenching liquid exerts considerable stress on the wheels, bearings, moving cylinders, etc., and any warpage can result in an alteration of the air gap distance.

In accordance with the invention, it has been discovered that these difficulties can be avoided and the desired air gap distance can be accurately achieved repeatedly without the necessity of adjustment by attaching a weir device directly to the spinning block.

Accordingly, it is an object of the invention to provide new and improved apparatus for liquid quenching of meltspun fibers. It is an object of the invention to provide means for achieving an accurately reproducible air gap between a spinneret and a body of quenching liquid.

Other objects, aspects and advantages of the invention will be apparent from a study of the specification, the drawings and the appended claims to the invention.

In the drawings, FIG. 1 is a diagrammatic illustration, partly in cross section, of a system embodying the present invention, and FIG. 2 is an enlargement of a portion of FIG. 1 showing additional features in cross section.

The process of the present invention is applicable to any melt spinnable synthetic organic thermoplastic polymer, for example, polyamides, polyesters, polyolefins such as polyethylene and polypropylene, polyurethanes, polyureas,

3,664,782 Patented May 23, 1972 ice vinyl halide polymers such as polyvinyl chloride, polyvinylidene chloride, and copolymers thereof, acrylic polymers such as polyacrylonitrile when sufiiciently plasticized to render it fusible, copolymers of acrylonitrile, polymers of halogenated olefins such as polychlorotrifiuoroethylene, polyacetals, polyanhydrides, polyformals, polyethers, polythioethers, polysulfides, polythioesters, polysulfones, polythioureas, polythioamides, polysulfonamides, polyimides, and polytriazoles. The preferred group of polyamides comprises such polymers as poly(hexamethyleneadipamide), poly(hexamethylene sebacamide), poly(epsiloncaproamide), and the copolymers thereof. Among the polyesters that may be mentioned, besides poly(ethylene terephthalate), are the corresponding copolymers containing sebacic acid, adipic acid, isophthalic acid as well as the polyesters containing recurrent units derived from glycols with more than two carbons in the chain, e.g., diethylene glycol, butylene glycol, decamethylene glycol and transbis-1,4-(hydroxymethyl)cyclohexane.

Referring now to the drawings, and to FIG. 1 in particular, the thermoplastic polymer is converted to its molten form in extruder 11 and passed through a passageway in spinning block 12 to a melt-spin metering pump driven by motor 13. Molten polymer is passed at a metered rate from the metering pump through screen packs to and through at least one spinning orifice in spinneret die plate 14 (FIG. 2) to form at least one, and usually a large plurality, of filaments 15. The filaments 15 pass through an air gap 16 into a body 17 of quenching liquid, such as water, maintained in quench tank 18. Quench tank 18 is positionable beneath spinning block 12 so that the upper surface of the quenching liquid contained in tank 18 is directly beneath the horizontally disposed spinning face 20 of spinneret die plate 14. The filaments 15 pass around a guide pin 19 and are withdrawn from quench tank 18 and then passed through a tension ladder comprising rods 28 and slotted pipes 29. The tension rods 28 create a constant tension source for the Godet feed roll 31 to pull against and also remove some of the quenching liquid from the filaments. [Pipes 29', which mave transversed slots therein, are connected by line 32 to vacuum pump 33 to remove excess quenching liquid from the filaments.

Feed roll 31 is positively driven at a uniform constant rate to pull the filaments 15 out of the quench bath and through the tension ladder. The filaments then pass around a snubbing pin 34 and a Godet draw roll 35. Rolls 31 and 35, as well as pin 34, can be heated to provide further drying of the filaments and/or to aid the drawing. The drawn filaments pass around a guide pin 36 and through a. traversing guide 37 to windup roll 38.

Make-up quenching liquid having a different temperature from that of the body 17 of quenching liquid can be passed through conduit 62 into quench tank 18 to control the temperature of the body of quench liquid. The rate of flow through conduit 62 can be regulated by valve 63, positioned therein. Valve 63 can be manipulated by temperature controller 64 responsive to a comparison of the actual temperature of the quench bath as measured by temperature sensor 65 and the desired temperature represented by setpoint 66.

horizontally outwardly from the upper extent of outer side wall 47. A plurality of bolts 49 are provided for vertically adjustably attaching the flange 48 of weir device 41 to the flange 44. The shank of each bolt 49 freely extends through an opening 51 in flange 44 and into threaded engagement with a corresponding threaded opening 52 in flange 48'. Rotation of the bolts 49 causes a change in the distance between the spinning face 20 and the upper edge of the side walls of weir device 41. If a substantially gas-tight shroud construction is desired, a circumferentially continuous flexible membrane 53 can be secured to the outer edges of flanges 44 and 48 by bands 54 and 55. A gaseous medium can be introduced into the shroud by way of conduit 56 (FIG. 1). This provides a substantially gas-tight enclosure excepting the opening 57 formed by the inner circumference of side wall 46 of weir device 41. The opening 57 is sufficiently larger than the outer boundary of the array of filaments -15 so that there is no contact between the filaments 15 and the weir device 41. The opening 57 is also sufliciently large to permit access to the spinneret for the purpose of wiping the spinning face.

The inner side wall 46 has a lesser height than the remainder of the side walls of weir device 41 to serve as the spillway for the passage of the excess quenching liquid from the body 17 of quenching liquid in tank 18 into the weir gutter. Conduit 58 is connected to the bottom wall 45 for draining liquid from the weir gutter. A flexible conduit 59 provides for communication between conduit 58 and a conduit 61 which extends through the wall of quench tank 18 so that liquid drained from the weir device 41 is passed to the exterior of tank 18 and then to a drain or to a sump for recycle. The inner wall 46, which serves as the spillway, has a sharply inclined upper edge which tapers downwardly toward the inside of the weir gutter to provide a greater degree of uniformity of the height of the meniscus.

While weir device 41 has been illustrated in the presently preferred toroidal forms, it is within the contemplation of the invention to utilize other circumferentially continuous annularly shaped weir gutters, for example, one formed by three or more straight gutter sections joined together at the ends, an oval gutter, a gutter having a curved path other than oval or circular, or combinations thereof. As used herein, the term circumferentially continuous annular shape is not limited to a circular shape, but includes any shape of gutter having the ends joined in a closed pathway. It is also possible to utilize weir devices which are not circumferentially continuous, such as a single straight section or two half-ring sections. The circumferentially continuous annular weir devices are preferred because of the greater uniformity of the air gap distance for each filament and of the flow of liquid in the area of instant contact by each filament. Although the outer side wall 47 could be provided with the reduced height to function as the spillway, or spillways could be provided in both the inner and outer side walls, it is presently preferred for the entire inner side wall to serve as the spillway. This provides for an upwardly flowing current of liquid in the area of initial contact of the filaments with the liquid, which offsets the tendency of the filaments to cause a whirlpool by the downward drag of the filaments on the liquid surface. Married filaments often result when the molten filaments are brushed against each other by the whirlpool action.

The exact distance between the spinning face and the quench liquid surface in my apparatus can be readily ascertained by providing graduation measurements on adjusting screws 49 as is the practice with micrometers, or by providing a calibrated scale on the vertical exterior surface of wall 47.

Variations in liquid level such as ripples on the surface of the quench liquid in the quench tank are not transmitted to the liquid surface maintained 'within the annular overflow weir of m invention.

Thus I have invented apparatus for maintaining a constant distance between the spinning face of a melt-spinning extruder and the quench liquid into which the molten filaments are passed from the extruder. This constant distance is maintained regardless of movements of the quench tank, whether deliberate movements for the purposes of tank cleaning, wiping of the spinning face, etc., or unintentional movements as may occur by movement of equipment and personnel within the building housing the extruder.

Reasonable variations and modifications are possible within the scope of the foregoing disclosure, the drawings and the appended claims to the invention.

I claim:

1. Apparatus comprising a spin block for melt spinning thermoplastic filaments, said spin block having a horizontally disposed spinning face containing at least one spinning orifice; a quench tank adapted to contain a body of quenching liquid, said quench tank being positionable beneath said spin block so that the upper surface of the quenching liquid contained in said quench tank would be directly beneath said spinning face; a weir device having a bottom wall and at least first and second side Walls extending generally upwardly from opposite sides of said bottom wall to form an enclosed wier gutter open at the top; conduit means for withdrawing liquid from said weir gutter and for passing the thus withdrawn liquid to the exterior of said quench tank; mounting means for vertically adjustably attaching said weir device to said spin block so that the vertical distance between said spinning face and the level of quenching liquid maintained in said quench tank is determined by the adjustment of said mounting means regardless of minor variations in the vertical spacing between said spinning face and said quench tank.

2. Apparatus in accordance with claim 1 wherein at least a portion of one of said side walls has a lesser height than the remainder of the side walls of said weir device to serve as the spillway for the excess quenching liquid from said body of quenching liquid into said weir gutter.

3. Apparatus in accordance with claim 2 wherein the spillway portion of the walls has an inclined upper edge tapering downwardly toward the inside of said weir gutter.

4. Apparatus in accordance with claim 1 wherein said weir gutter is in the form of a circumferentially continuous annular gutter with the opening formed by the inner circumference of said weir device being greater than the outer boundary of the array of filaments as the filaments pass through said opening into said body of quenching liquid.

5. Apparatus in accordance with claim 4 wherein said side wall is the circumferentially continuous outer side wall and said second side wall is the circumferentially continuous inner side wall and wherein the circumferentially continuous inner side wall has a lesser height than the circumferentially continuous outer side wall.

6. Apparatus in accordance with claim 5 wherein said weir device and said mounting means form a substantially gas-tight enclosure with said spinning face excepting said opening formed by the inner circumference of said weir device, and means for introducing a gaseous medium into said gas-tight enclosure.

7. Apparatus in accordance with claim 5 wherein said circumferentially continuous annular gutter is in the form of a toroid.

8. Apparatus in accordance with claim 7 wherein the upper edge of said circumferentially continuous inner side wall is in the form of a sharp edge tapering inwardly and downwardly with respect to the interior of said gutter.

9. Apparatus in accordance with claim 1 wherein said weir device has at least one mounting flange with a thread ed opening therein; and wherein said mounting means comprises at least one second flange secured to said spin block and having an opening therethrough, and each said at least one second flange having a bolt with the shank thereof freely extending through the opening in each second flange and into threaded engagement with the threaded opening in a respective one of said at least one mounting flange, whereby rotation of the at least one bolt will cause a change in the distance between said spinning face and the upper edge of the side walls of said weir device.

10. Apparatus in accordance with claim 1 further comprising means for sensing the temperature of said body of quenching liquid, and means for adding make-up quenching liquid having a different temperature to said quench tank at a rate responsive to the thus sensed temperature.

References Cited I SPENCER OVERHOLSER, Primary Examiner 10 M. O. SUTTON, Assistant Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,66A,782 1mm May 23, 1972 J. B. Nevin It is certified that error appears in the above-identified patent and. that said. Letters Patent are hereby corrected as shown below:

Column 1, line 5, the assignee "Phillips Petroleum Company" should read Phillips Fibers Corporation Column 1+, line 23, "wier" should read weir column 11,, line 51, after "said" insert first Column 5, line 2, after "each' insert said Signed and sealed this 13th day of March 1973.

(SEAL) Attest: I

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Commissioner of Patents Attesting Officer 

